In cold starting mode the exhaust system of a combustion engine is usually at ambient temperature. In the temperature range of the ambient temperature however catalytic system components of the exhaust system such as for example an oxidation catalytic converter or a nitric oxide storage catalytic converter as well as an SCR (selective catalytic reduction) catalytic converter are at a temperature level at which the respective catalytic system component cannot develop its function or at least only to a very limited extent. In order for the catalytic system components to become catalytically active, these have to be heated up through the hot exhaust gas flow. The exhaust system itself, however, with its system components, constitutes a thermal ballast in a manner of speaking, since the cold exhaust system cools down the exhaust gas flow even with optimum insulation. Accordingly, the temperature of the respective catalytic system component will increase the slower the further it is positioned in the direction of the end of the exhaust system.
In addition, the exhaust gas temperature even in low load ranges of the combustion engine can at least at times lie below the working temperature range of the respective catalytic system component, so that in this case a cooling-down of the catalytic system component below its working temperature range through the exhaust gas is possible.
These problem definitions with respect to the desired working temperature range of catalytic system components exemplarily described above can only be partially compensated for through an optimum insulation of the exhaust system or its system components.
Because of the catalytic system components not being active, the exhaust emission values that occur there are not tolerable and an immediate heating-up for example in cold starting mode is desirable and for example in a low load range, additional heating-up at least of the catalytic system components advantageous.
There is, therefore, an increasing need for possibilities of bringing the catalytic system components of an exhaust system up to working temperature as quickly as possible and/or to accurately and constantly maintain a working temperature range of a catalytic system component.
Accordingly, the present invention deals with the problem of stating an improved or at least an alternative embodiment for an exhaust system, its system components as well as for an associated operating method and for the use of a reactive heating system, which is more preferably characterized by a rapid heating-up behaviour of the exhaust system and/or its more preferably catalytic system components.
According to the invention, this problem is solved through the subjects of the independent Claims. Advantageous embodiments are the subject of the dependent Claims.